yes you are right in that the white backing is stopping the oring from falling out of the carrier.

my theory is that with no spacers the carrier might be sliding back and forth in the powertube and ther is enough space for the oring to fall out of the carrier as mentiond so therfor i started to thinking abut the problem and came out with a solution to try with fixating the carrier as this in theory atleast make things more predictable if thay not flopping around uncontrolably and also in my "experimenting" without spacers ther where contact between carrier and bolt as mentiond in my previous post.
note that im not claming my way is the right way but only one of the ways to tune LVL10 bolts.